1. Technical Field
This disclosure relates generally to surgical instrumentation, and more particularly, to a surgical dissector for harvesting veins.
2. Background of the Related Art
Surgical treatment of diseases such as cardiovascular disorders may require the removal of a section of a blood vessel from a patient for use elsewhere in the body. For example, the presence of obstructing lesions in an artery may be treated by the use of vascular replacements such as bypass grafts. By this procedure, normal circulation is restored by maintaining blood flow through an alternate path. In particular, bypass grafting consists of the anastomosis of a segment of a donor vessel to the aorta or the arteries in order to bypass the obstruction.
Donor vessels used in bypass grafting are typically the saphenous vein or the internal thoracic artery. The saphenous vein, which extends the length of the leg, is preferred when a relatively larger graft is required and a section of adequate length and diameter exists in either leg of the patient. Traditional surgical removal of the saphenous vein requires an incision along the leg extending the length of the vessel section to be removed. When a substantial section of vein is required, the resulting incision is necessarily long, particularly since it is advisable to over-estimate the length of vein needed. In fact, it is not uncommon for an incision to be made running the entire length of the leg, from the ankle to the groin, which can be over 40 inches in length. During the procedure, the surgeon typically incises the skin overlying the surface of the vein. When the required length of vein is exposed, the vein is freed from subcutaneous tissue by a combination of sharp and blunt dissection. Each branch of the vein is ligated and severed. The vein section is cut at both ends and removed from the patient. Subsequently, the incision is closed with sutures or metal clips.
Removal of veins by a long incision has a number of disadvantages. The formation and closure of the incision prolongs the surgical procedure and leaves a significant scar. Associated with the incision is the risk of infection, inflammation, and skin necrosis that may result. Additional surgeon time is required to close the incision, adding to the expense of the procedure. The procedure also increases the patient's discomfort and prolongs the recovery time. In some cases, the recovery period for the leg incision may exceed the recovery period required for the chest incision from the heart surgery.
The need for a less invasive method and instrumentation to remove the saphenous vein is recognized in the field. For example, in U.K. Patent No. 2,082,459, an apparatus is disclosed for harvesting the saphenous vein using small incisions. A center rod is inserted into the lumen of the vein, and the tubular body having a series of cutting blades is introduced over the center rod and passed along the vein to cut the tributaries and fatty tissue around the vein. U.S. Pat. No. 4,793,346 to Mindich discloses an apparatus having a plastic tube with an inner diameter slightly larger than the outer diameter of the vein and a knife blade at its leading end. The tube is then pushed along the vein while rotating the tube so as to sever branches of the vein by the knife blade. Electrical current is supplied to the knife blade to cauterize the ends of the severed branches.
Each of the instruments of the prior art described above are complex and expensive. Furthermore, they require the use of the same tool for dissection and for cutting. Consequently, surrounding subcutaneous tissue is severed rather than separated in a less traumatic fashion, e.g., by blunt dissection. Furthermore, there is a risk of damaging the saphenous vein by the sharp dissection tool.
U.S. Pat. No. 5,373,840 to Knighton discloses an endoscope and method for vein removal under visualization. A scope body is provided having a lumen extending therethrough. The scope body is inserted into a small incision near the vein. An annular dissecting ring is inserted through the scope body to dissect away the surrounding tissue, and a grasping tool may be inserted through the lumen to hold the vessel during the procedure. The scope body is advanced along the vein as it is dissected. When a side branch is encountered, the dissection tool is removed and a ligating-cutting tool is inserted through the lumen to sever the side branch.
This instrument is complex and expensive. Furthermore, sharp dissection of surrounding tissue is functionally limited to the diameter of the annular dissecting ring. The provision of a single lumen requires that several tools be inserted and withdrawn repeatedly into the same single lumen into which the vein is being drawn. This makes the procedure cumbersome for the surgeon and may risk damage to the saphenous vein.
It would be advantageous to provide an apparatus which could separate the skin and subcutaneous tissue from the vein in a minimally invasive manner. It would also be advantageous to provide a device facilitating the introduction of instrumentation to remove the vein without requiring repeated insertion and withdrawal from the apparatus.